Heat exchange device



Patented is, 28, 1942 'ATENT Fries 2,281,206 nan-r nxcnimci-z DEVICE Paul F. Schoen, Dear-born, Mich, assignor' to Bohn Aluminum & Brass Qorporatlon, Detroit, Mich., a corporation of Michigan Application rune 17, 1939, Serial No. 279,690 4 Claims. (or. 257-148) This invention relates to a heat-exchange device and to the method of producing the same.,

extruded from, aluminum or other suitable material. The tubing'is extruded with fins on both the inner and outer diameters, and the. tub- Fig. 1 is a plan view of a heat exchange device embodying the invention.

Fig. 2 is a section on line 2-2 of Fig. 1.

Fig. 3 is a fragmentary cross-section of the device.

The invention is illustrated in the drawing as a unit for application to a wall or ceiling of a cold storage room, although obviously the novel features may be used in heat exchange devices for other purposes.

The cooling unit illustrated consists of a single length of tubing I. which is extruded with a plurality of external finsll and with a plurality of internal fins l2. This tubing is preferably extruded from commercially pure aluminum, although other suitable materials may be used.'

At places where thetubing is to be bent. such as at I3, the outer fins are sheared oil to prevent any interference with the bending operation.

In order to give the fins of the tubing a spiral,

shape the length of the tubing to be spiraled, for example the straight run I, is twisted while under tension. This is preferably done by applying clamps to the outside of the tube at the fectly straight and gives an even and uniform spiral shape to the fins, the pitch of the spiral depending on the number of turns given to th movable clamp. The run it is preferably twisted while the entire piece It is a straight length, and it is to be understood that this first twisting operation does not twist the tube beyond the point I 6, so that the internal fins at the place 13 have not been spiraled. r A

The next operation-is to bend the tube at the and IS in order to provide a smooth tube adapted for connection with the tubing of a refrigeration system. The internal fins may also be removed at the ends I and I9 if desired.

Among the advantages of the above construc- .tion' are the fact that the twisting of the tube to spiral the fins elongates the edges 01' the fin which were extruded as thin as posible, thus thinning them and increasing their efllcieney for heat conduction. At the same time the tubing itself is shortened and thickened, thus increasing the safety factor on the tube. The spiral fins shape of the fins avoids any pockets in which condensation might collect.

The runs l4, l'5,.etc., need not be parts of a single tube, but can be separate pieces connected together or to a header by suitablefittings,

It will be clear to those skilled in the art that the tube used in the above unit can be fabricated into units of diflerenfishapes and dimensions to provide heat exchange unitsjor various types of installations.

ingv is twisted to give the fins a spiral form, which 10 place l3. In order to prevent collapse of the increases the heat-exchange efilciency and imtube and of the internal finsa "mouse" formed p v t phys al pr perties of the tu in If of a plurality of flexible elements, such as wires, t tu is to be t in f rm a h a is drawn into the tubing to the place It, and ex a u t, the par t be be is ept n o e the tube isthen bent in the desired direction. pliable condition by not twisting it, and the ex- 15 The t run I5 1 th tubing is then spiraled, t rna fi s are removed p r t bendin and the bend I! is next formed, these operations While preferred forms of the invention are disbeingv repeated until the t m g i 6105 herein Purposes mustl'atim, Vari' formed. As an alternative method the different Ous changes may be made in the structure with" runs of the tubing can be spiraled while the tubout departing from the spirit of the invention 20 mg m is in one straight piece ifsuitable'arrangeas herein set forth and claimed' mentsare made to keep the sections where the These and other objects and advantages of bends are to be made in their original untwisted' the invention will become apparent as the decondition 22 2 2233533 25 The external fi'ns are removed at the ends 18 I claim: Y 1. A heat exchange unit comprising a single length of tubing formed into straight runs connected by bent portions, each of the straight runshaving external spiral fins and internal spiral fins, the bent portions having internal fins and smooth external surfaces free of fins, the internal fins on each bent portion being in non-spiralform, a portion at each end of the length of tubing having smooth external surfaces.

3. A heat exchange unit comprising a single length of tubing formed into straight runs connected by bent portions, the tubing having internal longitudinal fins throughout its length, each of the straight runs having external spiral fins,

the internal fins on each straight run having spiral form, the bent portions having smooth external surfaces free of fins, the internal fins on each bent portion being in non-spiral form, a portion at each end of the length of tubing having smooth external surfaces.

4. A heat exchange unit comprising a single length of aluminum tubing formed into straight runs connected by bent portions, the tubing having internal longitudinal fins throughout its length, each of the straight runs having external spiral fins. the internal fins on each straight run having spiral form, the bent portions having smooth external surfaces free of fins, the internal fins on each bent portion being in non-spiral form, a portion at each end of the length of tubing having smooth external surfaces.

- PAUL F. SCHOEN. 

